Signaling RSVP-TE tunnels on a shared MPLS forwarding plane
draft-ietf-mpls-rsvp-shared-labels-03
MPLS Working Group H. Sitaraman
Internet-Draft V. Beeram
Intended status: Standards Track Juniper Networks
Expires: March 14, 2019 T. Parikh
Verizon
T. Saad
Cisco Systems
September 10, 2018
Signaling RSVP-TE tunnels on a shared MPLS forwarding plane
draft-ietf-mpls-rsvp-shared-labels-03.txt
Abstract
As the scale of MPLS RSVP-TE networks has grown, so the number of
Label Switched Paths (LSPs) supported by individual network elements
has increased. Various implementation recommendations have been
proposed to manage the resulting increase in control plane state.
However, those changes have had no effect on the number of labels
that a transit Label Switching Router (LSR) has to support in the
forwarding plane. That number is governed by the number of LSPs
transiting or terminated at the LSR and is directly related to the
total LSP state in the control plane.
This document defines a mechanism to prevent the maximum size of the
label space limit on an LSR from being a constraint to control plane
scaling on that node. It introduces the notion of pre-installed 'per
Traffic Engineering (TE) link labels' that can be shared by MPLS
RSVP-TE LSPs that traverse these TE links. This approach
significantly reduces the forwarding plane state required to support
a large number of LSPs. This couples the feature benefits of the
RSVP-TE control plane with the simplicity of the Segment Routing MPLS
forwarding plane.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
Sitaraman, et al. Expires March 14, 2019 [Page 1]
Internet-Draft RSVP-TE Shared Labels September 2018
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
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This Internet-Draft will expire on March 14, 2019.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Allocation of TE Link Labels . . . . . . . . . . . . . . . . 5
4. Segment Routed RSVP-TE Tunnel Setup . . . . . . . . . . . . . 5
5. Delegating Label Stack Imposition . . . . . . . . . . . . . . 7
5.1. Stacking at the Ingress . . . . . . . . . . . . . . . . . 8
5.1.1. Stack to Reach Delegation Hop . . . . . . . . . . . . 8
5.1.2. Stack to Reach Egress . . . . . . . . . . . . . . . . 9
5.2. Explicit Delegation . . . . . . . . . . . . . . . . . . . 10
5.3. Automatic Delegation . . . . . . . . . . . . . . . . . . 10
5.3.1. Effective Transport Label-Stack Depth (ETLD) . . . . 10
6. Mixing TE Link Labels and Regular Labels in an RSVP-TE Tunnel 11
7. Construction of Label Stacks . . . . . . . . . . . . . . . . 12
8. Facility Backup Protection . . . . . . . . . . . . . . . . . 13
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